High Melt Strength Polypropylene

Polypropylene has low melt strength and lack of strain hardening behavior, due to its linear chain structure. This may result in problems in applications that require melt extension. Problems include too narrow processing windows, non-uniform foam cell size and pin-holes in thermoformed sheet.

Peroxydicarbonates for high melt strength PP

Now AkzoNobel has developed and patented a new technology which overcomes these problems. Reaction of PP powder with a special class of organic peroxides - peroxydicarbonates - in an extruder introduces long chain branches and creates high melt strength PP (HMS-PP).

HMS-PP exhibits a decreased MFI, a broader MWD by long chain branching, an increased melt strength and die swell, and an improved strain hardening and melt elasticity. This allows for applications such as PP foaming, thermoforming and blow molding.

FDA food contact approval for all HMS-PP applications

The preferred peroxydicarbonate is Perkadox® 24L. The best performance is obtained when mixing the product with either PP reactor grade (powder, beads) or milled PP pellets, prior to extrusion. Only carbon dioxide and cetyl alcohol are released which add no smell to the final resin. FDA food contact approval (2.0% max.) has been obtained for all HMS-PP applications, including foamed food trays for microwave use.

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